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How to Setup a Garden Irrigation System

I doubt there would be a gardener alive who doesn’t understand that watering the garden is one of the most important activities when it comes to gardening. Stop watering your plants in the middle of summer and you’ll soon realise that your choice of fertiliser, the style of pruning and the quality of garden tools you possess have very little bearing on keeping your garden alive.

But, watering costs time and the bigger the garden…the more time it consumes to keep it moist. Enter stage right the Garden Irrigation System.

Garden irrigation, or reticulation as some refer to it, is a system that involves moving water from one point to multiple others via a network of solenoids, PVA pipe, sprinklers and an automatic controller. The whole system can be programmed automatically to turn on whenever you want – even while you’re asleep.

So how do you go about setting up a garden irrigation system. Well let’s start with the basics and breakdown each step to make it easy.

Garden Irrigation System Source

From the very beginning, there needs to be a source of water to tap into. This may be; a well, a soak, a drilled bore into artesian water, a large rainwater tank or directly into scheme water – with the last option being the least preferred. With the four preceding options they will all require some type of pump (they all differ depending on the size and complexity of your irrigation system.

Irrigation Pipes

To move water around your property it’s going to take a network of PVA pipes. Obviously, it’s much easier to install before you add your lawn, plants and other landscaping features but it can still be done after all these have grown to maturity.

The most important pipe is the mainline. This runs the perimeter of your garden and will eventually house all the other pipes coming off it. With the mainline, bigger is better and you should use a size of at least 40-50mm (1.5-2in) pipe. Using pipe that’s too small will bottleneck the reticulation system causing a trickle instead of a flow that is less than ideal.

TIP: When installing irrigation pipe always go down in size – never up. Increasing the size means serious drops in pressure and your garden irrigation system will fail you.

The Dreaded Solenoids

When planning a garden irrigation system for your property you need to calculate how many stations you want. The first step is calculating the flow-rate from your water source. Once you know this you can begin to divide your garden into a number of sections; Lawn 1, Lawn 2, Garden Bed 1, Garden Bed 2 etc according to the number of sprinklers you can fit onto each station.

Once you’ve divided your garden into these lots you can begin to add your solenoids directly from the mainline. One solenoid per station. The solenoid acts as the gateway between watering each station or not and can be connected via 12v wiring to come on automatically. From the solenoids comes the stations main pipe which is usually 25mm (1inch).

As you branch off this main pipe you can degrade the sizes and even change the pipe material from PVA to polypropelene (poly-pipe) depending on the requirements of each station. If the station is just to water a lawn then you will need to keep the pipe at least at 20mm PVA. Shrubs, trees and garden beds are best irrigated with poly-pipe that can be weaved, and altered, throughout the garden and makes connection of tricklers very simple.

Choosing the Rght Sprinklers

You’re almost on the home straight now as one of the final items come into view – the sprinklers. There are so many types; shrub sprays, misters, bubblers, tricklers, pop-ups that it can become a little overwhelming. However, the reality of the situation is that choosing the right sprinklers isn’t the most final decision that it appears to be – most sprinklers can be changed later if you get it wrong.

As a rule of thumb pop-ups are for lawns only. This allows the garden irrigation system to function when it needs to water the lawn but pops back down to below ground-level so that the lawn can be enjoyed without tripping on them. If you have a larger lawn than normal you may need to consider gear-driven sprinklers that offer better efficiencies.

Once you move into the garden beds it becomes a question of ‘what do I actually want to water?’ If it’s the whole garden bed then shrub sprays are your best option. If you want to conserve water and can afford to deliver it to each plant individually then bubblers or tricklers are the right fit.

Picking the Right Automatic Controller

The final step in creating this whole garden irrigation system is picking an automatic controller. This is the ‘engine room’ of the whole system and automatically controls when each station turns on, or off.

To use an automatic controller you will need to have run 12v cable to each of the solenoids. Each solenoid has two wires that require attaching: one goes to a colour (ie. red, green, blue etc) while the second becomes the common (black). It doesn’t matter which of the two is the common or the coloured line.

In order to do this you will need to run a 12v line from the water source pump (usually brown) to the controller. The pump will also need the common black line running from it as well. You need to think of the common line as though it has to go from the water source, touch each solenoid and then back to the controller as a continuous length.

The black common line then fits into the controller – it’s usually designated ‘common’ so you can’t stuff it up. Then each colour represents each of the solenoids that they’re attached to. Line 1 = station 1 etc.

Choosing the right controller is making sure that it has enough stations to handle your irrigation system. Plus it should have different schedules so that you have a little more control as to when a station comes on. For example, you may want to water your lawn every two days but your garden beds every three. Having extra schedules allows this without making your life too complicated.